Exemplos de uso de CNO cycle em Inglês e suas traduções para o Português
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Our Sun produces 10% of its energy from the CNO cycle.
In stars of slightly over,the carbon-nitrogen-oxygen fusion reaction(CNO cycle) contributes a large portion of the energy generation.
Only 0.8% of the energy generated in the Sun comes from the CNO cycle.
The effects of the CNO cycle appear at the surface, with lower 12C/13C ratios and altered proportions of carbon and nitrogen.
When helium fusion comes to an end at the core,convection mixes the products of the CNO cycle.
O is primarily made by the burning of hydrogen into helium during the CNO cycle, making it a common isotope in the hydrogen burning zones of stars.
Stars in the upper main sequence have sufficiently high core temperatures to efficiently use the CNO cycle.
Because the CNO cycle is very temperature sensitive, the energy generation is heavily concentrated at the center of the star, which results in a convection zone about the core.
Hydrogen plays a vital role in powering stars through the proton-proton reaction and the CNO cycle of nuclear fusion.
At a stellar core temperature of 18 Million Kelvin,the PP process and CNO cycle are equally efficient, and each type generates half of the star's net luminosity.
Beyond about 8-12 M☉, depending on metallicity,stars have hot massive convective cores on the main sequence due to CNO cycle fusion.
In massive stars(above 10 M☉)the rate of energy generation by the CNO cycle is very sensitive to temperature, so the fusion is highly concentrated at the core.
The proton-proton chain reaction is one of several fusion reactions by which stars convert hydrogen to helium,the primary alternative being the CNO cycle.
This is suitable for stars at least as massive as the Sun,exhibiting the CNO cycle, and gives the better fit R∝ M0.78.
Such stars also show nitrogen enhancement at the surface at a very young age, caused by changes in the proportions of carbon andnitrogen due to the CNO cycle.
In the CNO cycle, four protons fuse, using carbon, nitrogen, and oxygen isotopes as catalysts, to produce one alpha particle, two positrons and two electron neutrinos.
The emission spectrum is produced in a powerful dense stellar wind, andthe enhanced levels of helium and nitrogen arise from convectional mixing of CNO cycle products to the surface.
The effects of the CNO cycle appear at the surface during the first dredge-up, with lower 12C/13C ratios and altered proportions of carbon and nitrogen.
During a star's evolution, convective mixing episodes bring material in which the CNO cycle has operated from the star's interior to the surface, altering the observed composition of the star.
Other less convincing theories, such as CNO cycle unbalancing and core helium flash have also been proposed as mechanisms for carbon enrichment in the atmospheres of smaller carbon stars.
The majority of these occur in within stars, andthe chain of those nuclear fusion processes are known as hydrogen burning(via the proton-proton chain or the CNO cycle), helium burning, carbon burning, neon burning, oxygen burning and silicon burning.
The hydrogen shell,fusing via the temperature-sensitive CNO cycle, greatly increases its rate of energy production and the stars is considered to be at the foot of the red-giant branch.
Hans Bethe and Charles L. Critchfield had derived the Proton proton chain(pp-chain) in 1938, and Carl von Weizsäcker andHans Bethe had independently derived the CNO cycle in 1938 and 1939, respectively, to show that the conversion of hydrogen to helium by nuclear fusion could account for stellar energy production.
The nitrogen seen in the spectrum of WNh stars is still the product of CNO cycle fusion in the core, but it appears at the surface of the most massive stars due to rotational and convectional mixing while still in the core hydrogen burning phase, rather than after the outer envelope is lost during core helium fusion.
This ejection process uncovers in succession, first the nitrogen-rich products of CNO cycle burning of hydrogen(WN stars), and later the carbon-rich layer due to He burning WC and WO-type stars.
During a star's evolution, convective mixing episodes moves material, within which the CNO cycle has operated, from the star's interior to the surface, altering the observed composition of the star.